GM Service Manual Online
For 1990-2009 cars only

Refer to Engine Controls Schematics

PCM Fuel Tank Inputs


Object Number: 590098  Size: FS
Engine MaxiFuses, Underhood Fuses and Ignition Main Relay
Ground G302 2 of 2
Ground G113
Ground G113
Handling ESD Sensitive Parts Notice
Engine Controls Component Views
Powertrain Control Module Description
PCM Emission Inputs
Crankshaft and Camshaft Position Sensor
OBD II Symbol Description Notice
.

Circuit Description

The PCM controls the fuel pump relay by supplying switched ignition voltage to the fuel pump relay coil. When the ignition switch is first turned On, the PCM energizes the fuel pump relay. The relay contacts close applying power to the fuel pump. The fuel pump relay will remain On as long as the engine is running or cranking and the PCM is receiving reference pulses. If no reference pulses are present, the PCM de-energizes the fuel pump relay within 2 seconds. With the engine stopped, the fuel pump can be turned On with a scan tool.

If the PCM detects a problem on the relay control circuit, DTC P0230 will set. Use this table if DTC P0230 is not set and a problem exists with the fuel pump.

Diagnostic Aids

Notice: Use the connector test adapter kit J 35616-A for any test that requires probing the following items:

   • The PCM harness connectors
   • The electrical center fuse/relay cavities
   • The component terminals
   • The component harness connector
Using this kit will prevent damage caused by the improper probing of connector terminals.

If the problem is intermittent, refer to Intermittent Conditions .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Command both the ON and OFF states. Repeat the commands as necessary.

  2. This step determines if the condition is located on the coil side or the switch side of the circuit.

  3. This step verifies that the PCM is providing voltage to the fuel pump relay.

  4. This step tests for an open in the ground circuit to the fuel pump relay.

  5. This step determines if a voltage is constantly being applied to the fuel pump relay.

  6. This step determines if the condition with the circuit is intermittent. If the fuse does not open, inspect the supply voltage circuit between the fuse and the fuel pump for an intermittent condition.

Fuel Pump Electrical Diagnosis (wo/Jumper Harness)

Step

Action

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, command the fuel pump relay ON and OFF.

Does the fuel pump turn ON and OFF?

Go to Intermittent Conditions

Go to Step 3

3

With a scan tool, command the fuel pump relay ON and OFF.

Do you hear a click when you command the fuel pump relay ON and OFF?

Go to Step 9

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Disconnect the fuel pump relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the control circuit of the fuel pump relay with a test lamp that is connected to a good ground.
  5. With a scan tool, command the fuel pump relay ON and OFF.

Does the test lamp turn ON and OFF?

Go to Step 5

Go to Step 6

5

  1. Connect a test lamp between the control circuit of the fuel pump relay and the ground circuit of the fuel pump relay.
  2. With a scan tool, command the fuel pump relay ON and OFF.

Does the test lamp turn ON and OFF?

Go to Step 19

Go to Step 22

6

Does the test lamp remain illuminated with each command?

Go to Step 7

Go to Step 8

7

  1. Disconnect the PCM. Refer to Powertrain Control Module Replacement/Programming .
  2. Test the control circuit of the fuel pump relay for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 27

Go to Step 26

8

  1. Disconnect the PCM. Refer to Powertrain Control Module Replacement/Programming .
  2. Test the control circuit of the fuel pump relay for a short to ground or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 27

Go to Step 20

9

Turn ON the ignition, with the engine OFF.

Does the fuel pump operate continuously?

Go to Step 10

Go to Step 11

10

  1. Turn OFF the ignition.
  2. Disconnect the fuel pump relay.
  3. Turn ON the ignition, with the engine OFF.

Does the fuel pump operate continuously?

Go to Step 21

Go to Step 25

11

Is the fuel pump fuse open?

Go to Step 12

Go to Step 14

12

  1. Remove the fuel sender access panel. Refer to Fuel Sender Assembly Replacement .
  2. Test the supply voltage circuit of the fuel pump for a grounded circuit between the fuel pump fuse and the fuel pump. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
  3. Replace the fuel pump fuse if necessary.

Did you find and correct the condition?

Go to Step 27

Go to Step 13

13

  1. Install all disconnected electrical components.
  2. Install a new fuel pump fuse.
  3. With a scan tool, turn ON the fuel pump.

Is the fuel pump fuse open?

Go to Step 24

Go to Intermittent Conditions .

14

  1. Turn OFF the ignition.
  2. Disconnect the fuel pump relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the battery positive voltage circuit of the fuel pump relay switch with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 15

Go to Step 23

15

Connect a 15 amp fused jumper wire between the battery positive voltage circuit of the fuel pump relay switch and the supply voltage circuit of the fuel pump.

Does the fuel pump operate?

Go to Step 19

Go to Step 16

16

  1. Remove the fuel sender access panel. Refer to Fuel Sender Assembly Replacement .
  2. Test the supply voltage circuit of the fuel pump for an open or high resistance between the fuel pump relay and the fuel pump. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 27

Go to Step 17

17

Important: Visually/physically inspect the ground circuit for being tight, for corrosion on terminals, or for damage to the wiring harness.

Test the ground circuit of the fuel pump for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 27

Go to Step 18

18

Inspect for poor connections at the fuel pump. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 27

Go to Step 24

19

Inspect for poor connections at the fuel pump relay. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 27

Go to Step 25

20

Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 27

Go to Step 26

21

Repair the supply voltage circuit of the fuel pump for a short to voltage. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 27

--

22

Repair the open fuel pump relay ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 27

--

23

Repair the battery positive voltage circuit of the fuel pump relay switch. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 27

--

24

Important: Inspect for poor connections at the fuel pump within the fuel tank, before replacing the fuel pump.

  1. Replace the fuel pump. Refer to Fuel Sender Assembly Replacement
  2. Replace the fuel pump fuse if necessary.

Did you complete the replacement?

Go to Step 27

--

25

Replace the fuel pump relay.

Did you complete the replacement?

Go to Step 27

--

26

Replace the PCM. Refer to Powertrain Control Module Replacement/Programming

Did you complete the replacement?

Go to Step 27

--

27

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2